This invention relates to a vehicle display lighting device, particularly, to a lighting device using a light emitting diode (LED) to directly illuminate an interior of a vehicle display such as a speedometer, a tachometer, etc.
There are numerous conventional vehicle display lighting devices used to illuminate a dashboard display of a vehicle. These conventional lighting devices include indirect lighting devices, edge-light lighting devices, transmission lighting devices, and direct lighting devices.
The indirect lighting device has a light source disposed inside a vehicle display or at a rear side of a display dial. The light from the light source radiates toward a front side of the display dial and is reflected by an interior surface of a display case. The reflected light indirectly lights up various symbols on the display dial and an indicator pointer.
The edge-light lighting device includes a display dial having a light guide plate formed of a transparent synthetic resin. A light source is arranged inside the vehicle display to direct the light toward an edge portion of the dial. The display dial guides the light therein and radiates the incident light toward a front side of the display dial, thereby illuminating the symbols of the display dial as well as the indicator pointer.
The transmission lighting device has a display dial formed from a transparent or semi-transparent material. A display surface of the display dial is made opaque except for the symbols and indicia formed thereon, which are transparent or semi-transparent and form light-transmitting portions. A light source is arranged inside the vehicle display so as to emit light from the rear side of the display dial toward the light-transmitting portions corresponding to the symbols. The symbols of the display dial and the indicator pointer are illuminated.
The direct lighting device has a light source disposed either at/or in front of the display dial. The light source directly illuminates the front surface of the display dial including the display symbols and the indicator pointer.
In each of the lighting devices described above, an incandescent lamp is generally used as the light source. With the exception of the direct lighting device, the light source is disposed inside the vehicle display, which requires a special space inside the vehicle display for installation of the light source. This increases the thickness or depth of the vehicle display and results in a complicated internal structure. Moreover, since the light is radiated from inside the vehicle display to the front side of the display dial, a transmission path of the light becomes comparatively long. Consequently, the light is attenuated, so that luminous efficacy of the light source is possibly lowered. Each of these devices has potential advantages but poses significant drawbacks. The transmission lighting device is known for increasing visibility of the vehicle display. Its luminous efficacy, however, is lessened depending on a transmissivity of the light-transmitting portion of the dial. The conventional direct lighting device is ideal in a viewpoint of the luminous efficacy. The direct lighting device, however, radiates the light from either an upper front side or lower front side of the display dial, while an optical axis thereof is inclined to the plane of the display dial. As a result, the illumination differs between the upper side and the lower side of the display dial. Furthermore, the indicator pointer casts a shadow on the front surface of the display dial. Thus, the visibility of the display is reduced.
It is an object of the present invention to provide a vehicle display lighting device having a simplified internal structure.
It is another object of the present invention to provide a vehicle display lighting device that results in a vehicle display having a reduced thickness.
It is another object of the present invention to provide a vehicle display lighting device having improved luminous efficacy.
It is another object of the present invention to provide a vehicle display lighting device having uniform illumination across the entire display dial.
It is another object of the present invention to provide a vehicle display lighting device that prevents an indicator pointer from casting a shadow on the display dial.
Additional objects and advantages of the invention are set forth, in part, in the description which follows, and, in part, will be apparent to one of ordinary skill in the art from the description and/or practice of the invention.
In response to the foregoing challenges, applicants have developed an innovative vehicle display lighting device for a vehicle display having a display dial. The display dial has a front surface, an outer circumference and at least one indicator pointer spaced from the front surface. In accordance with the present invention, the lighting device includes a light emitting assembly arranged along the outer circumference of the display dial in front of the front surface. The light emitting assembly directs lights across at least the front surface of the display dial. The lighting device also includes a control assembly for controlling the operation of the light emitting assembly.
In accordance with the present invention, it is contemplated that the light emitting assembly may include one or more light sources for emitting light, and a transmitting assembly for radiating the light from the light source across at least the front surface of the display dial.
The transmitting assembly is positioned adjacent the outer circumference of the display dial. The transmitting assembly may include a light guide ring positioned adjacent the outer circumference of the display dial. The light from the light sources is transmitted through the light guide ring. The light guide ring may include a coating on at least one surface to direct light from the light source inwardly to the center of the front surface.
It is contemplated that the light guide ring may direct light only across the front surface of the display dial. With this arrangement, the light guide ring is positioned adjacent the outer circumference between the front surface and the indicator pointer.
It is also contemplated that the light guide ring may direct light across the front surface of the display dial and the indicator pointer. With this arrangement, the light guide ring may be positioned adjacent the outer circumference in front of the front surface and the indicator pointer. Alternatively, the light guide ring may positioned adjacent the outer circumference such that the light guide ring extends from the front surface to a point in front of the indicator pointer.
In accordance with the present invention, the light guide ring includes a pair of free ends. At least one light source may be positioned adjacent each free of the light guide ring. A light source housing is secured to each free end of the light guide ring. The lighting device also includes a flexible printed circuit board. Each light source housing is secured to the flexible printed circuit board. The light sources are electrically connected to the flexible printed circuit board. The control assembly is also electrically connected to the flexible printed circuit board.
Alternatively, the transmitting assembly may include a reflection mirror positioned adjacent the outer circumference of the display dial. The light from the light source is reflected by the reflection mirror toward the center of the front surface. It is contemplated that a plurality of light sources may be located adjacent the outer circumference of the display dial adjacent the reflection mirror.
In accordance with the present invention, the light emitting assembly may include plurality of light sources for emitting light. The plurality of light sources are located adjacent the outer circumference of the display dial. The light sources are electrically connected to a flexible printed circuit board that is positioned adjacent the outer circumference of the display dial. The plurality of light sources may emit light only across the front surface of the display dial. With this arrangement, the light sources are positioned adjacent the outer circumference between the front surface and the indicator pointer. It is also contemplated that the light sources may emit light across the front surface of the display dial and the indicator pointer. With this arrangement, the light sources are positioned adjacent the outer circumference in front of the front surface and the indicator pointer.
In response to the foregoing challenges, applicants have also developed an innovative lighting device having a support member positioned in front of the front surface and the indicator pointer. The support member includes an end portion that covers a portion of the front surface and the indicator pointer. The lighting device further includes a light emitting assembly located on the support member. The light emitting assembly may include a plurality of light sources for emitting light. The light emitting assembly is adapted to direct light across the front surface and the indicator pointer of the display dial. The lighting device also includes a control assembly for controlling the operation of the light emitting assembly.